Imaging characteristics of scintimammography using parallel-hole and pinhole collimators

The purpose of the study is to investigate the imaging characteristics of scintimammography (SM) using parallel-hole (PR) and pinhole (PN) collimators in a clinical setting. Experimental data were acquired from a phantom that models the breast with small lesions using a low energy high resolution (LEHR) PR and a PN collimator. At close distances, the PN collimator provides better spatial resolution and higher detection efficiency than the PR collimator, at the expense of a smaller field-of-view (FOV). Detection of small breast lesions can be further enhanced by noise smoothing, field uniformity correction, scatter subtraction and resolution recovery filtering. Monte Carlo (MC) simulation data were generated from a realistic 3D MCAT phantom that models the Tc-99m sestamibi uptake and attenuation distributions in an average female patient. The scatter to primary ratio (S/P) decreases from the base to the tip of the breast. For PR collimation, S/P is higher in the left than right breast due to scatter of photons from the heart. For PN collimation, S/P is highest at the base and lowest at the tip of the breast as compared to PR collimation. It is higher in the right than left breast due to contributions from organ uptakes in the body. Results from the study add to understanding of the imaging characteristics of SM using PR and PN collimators and assist in the design of data acquisition and image processing methods to enhance the detection of breast lesions using SM